From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lelv0142.ext.ti.com ([198.47.23.249]:34632 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725757AbeIQQ1y (ORCPT ); Mon, 17 Sep 2018 12:27:54 -0400 From: Tomi Valkeinen To: , Daniel Vetter , Dave Airlie CC: Tomi Valkeinen , Subject: [PATCH] drm: fix use of freed memory in drm_mode_setcrtc Date: Mon, 17 Sep 2018 14:00:54 +0300 Message-ID: <20180917110054.4053-1-tomi.valkeinen@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: stable-owner@vger.kernel.org List-ID: drm_mode_setcrtc() retries modesetting in case one of the functions it calls returns -EDEADLK. connector_set, mode and fb are freed before retrying, but they are not set to NULL. This can cause drm_mode_setcrtc() to use those variables. For example: On the first try __drm_mode_set_config_internal() returns -EDEADLK. connector_set, mode and fb are freed. Next retry starts, and drm_modeset_lock_all_ctx() returns -EDEADLK, and we jump to 'out'. The code will happily try to release all three again. This leads to crashes of different kinds, depending on the sequence the EDEADLKs happen. Fix this by setting the three variables to NULL at the start of the retry loop. Signed-off-by: Tomi Valkeinen Cc: stable@vger.kernel.org --- drivers/gpu/drm/drm_crtc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 2f6c877299e4..2ad14593fb23 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -570,9 +570,9 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, struct drm_mode_crtc *crtc_req = data; struct drm_crtc *crtc; struct drm_plane *plane; - struct drm_connector **connector_set = NULL, *connector; - struct drm_framebuffer *fb = NULL; - struct drm_display_mode *mode = NULL; + struct drm_connector **connector_set, *connector; + struct drm_framebuffer *fb; + struct drm_display_mode *mode; struct drm_mode_set set; uint32_t __user *set_connectors_ptr; struct drm_modeset_acquire_ctx ctx; @@ -601,6 +601,10 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, mutex_lock(&crtc->dev->mode_config.mutex); drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE); retry: + connector_set = NULL; + fb = NULL; + mode = NULL; + ret = drm_modeset_lock_all_ctx(crtc->dev, &ctx); if (ret) goto out; -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki